phpBB by Przemo : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('971b1bca6eba6effeb0ec913d73d4411', -1, 1540115901, 1540115901, '36a16418', -1, 0, 0)

Line : 445
File : sessions.php